Touch screen systems such as capacitive touch screens generally include a sensor matrix or array and a control circuit. The control circuit measures capacitive loading on the array to determine the position or location of the touch on the array. The array is mounted on a translucent screen or substrate. The control circuit generally receives electrical power from power circuitry which is electrically coupled to the control circuit. The power circuitry can be comprised of a power supply and a fan. Touch screen systems also can include various computer equipment such as a motherboard, ISA cards, hard drives, memory, floppy drives, graphic devices, or other equipment for enhancing the functions and capabilities of the touch screen system.
The touch screen is typically utilized in conjunction with a graphic overlay or sheet, a liquid crystal display, and other light sources. The display projects variable images upon or through the touch screen, and the graphic overlay provides semi-permanent menus, symbols and backgrounds for the touch screen. The graphic overlay is typically provided in front of the touch screen and the display and is exposed to the user. Such a location for the graphic overlay makes it prone to wear, difficult to replace, and interferes with the sensing operation of the touch screen.
Prior art touch screen systems including the touch screen, graphic sheet, display, and computer equipment are generally contained in an enclosure comprised of a front bezel or shroud and a back enclosure. The touch screen components including the control circuit, sensor array, and power circuits are located on a single chassis between the shroud and the rear enclosure. The display and computer equipment are also located between the rear enclosure and the shroud. The rear enclosure generally contains the more bulky computer equipment, electronic components and other devices.
Heretofore, when service personnel replaced the graphic sheet due to wear or a new application requirement, the shroud had to be removed from the rear enclosure and the touch screen system had to be partially disassembled to gain access to the graphic sheet. Prior art configurations of the enclosure and touch screen system including the placement of the graphic sheet are particularly disadvantageous because the menus, instructions or other customized graphics on the graphic sheet are revised on a regular basis. Thus, the prior art configuration for touch screen enclosures and touch screen systems increases the time and cost associated with replacing the graphic sheet by requiring the entire touch screen system to be disassembled.
Thus, there is a need for an enclosure system having an easily insertable and removable graphic sheet. There is also a need for a graphic underlay which is positioned between the display and the touch screen and which does not interfere with the sensing operation of the touch screen.